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Ladder Logic ElementsAdvancedAdvanced
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Updated 2025-11-10
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LIFO Load

LFL - LIFO Load

Last-In-First-Out stack instruction that pushes data onto stack.

Key Takeaways

  • Last-In-First-Out stack instruction that pushes data onto stack.
  • Advanced-level topic in Ladder Logic Elements

Detailed Definition

Last-In-First-Out stack instruction that pushes data onto stack. This term is essential for understanding ladder logic in industrial automation and PLC programming.

LIFO Load is part of the visual vocabulary of ladder logic, the relay-derived language that virtually every PLC vendor still supports. Last-In-First-Out stack instruction that pushes data onto stack.

Inside the scan cycle, LIFO Load is processed during the program execution step. Its behaviour is deterministic — given the same inputs, it always produces the same outputs in the same time — which is exactly what industrial control demands.

In a multi-vendor world, LIFO Load appears with subtle syntactic differences across Siemens TIA Portal, Rockwell Studio 5000, Mitsubishi GX Works, and Codesys-based IDEs — the IEC 61131-3 standard governs the concept, but vendors layer their own conventions on top.

Common Questions

What is LIFO Load?

Last-In-First-Out stack instruction that pushes data onto stack.

What prerequisites are needed to understand LIFO Load?

As an advanced-level concept, LIFO Load requires a solid foundation in PLC fundamentals and intermediate programming concepts. It's recommended to have hands-on experience with Ladder Logic Elements before diving deep into this topic.

What are related concepts I should learn?

To fully understand LIFO Load, you should also familiarize yourself with TON (Timer On-Delay), TOF (Timer Off-Delay), and CTU (Count Up). These concepts work together in industrial automation systems.

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About Ladder Logic Elements

Contacts, coils, timers, counters, and ladder diagram components

Total Terms:70
Difficulty:Beginner to Intermediate

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